The substituent–arene orbital interactions in 1,4-C6H4Fp2 where Fp = (╖5-C5H5)Fe(CO)2, are compared with the interactions in the series C6H4X2, X=BH2, NH2, CH2 and O, by using unparameterized Fenske-Hall molecular orbital calculations. Analysis of the MOs, the Mulliken populations of the fragments, and the overlap populations provides an understanding of the extent and nature of the relative σ and π interactions between the arene and the various substituents. In our fragment analysis the interactions of the main-group fragments are compared easily with the interactions of the transition-metal fragment. Although it has been suggested that 1,4-C6H4Fp2 has a significant contribution from a quinone-like resonance structure, our study of the bonding reveals very little π character in the Fe–arene bonds.